Having worked in a pro tennis shop for the good part of 2 years, i've learnt that it depends on the person.
Guys that actaully post regularly on this board generally know about racquets, so are not starstruck 'he uses this so it must be good...etc'
Its when the kids come into the shop and say 'is this the nadal racquet' and 'is this the federer racquet' etc, its just been well marketed to them. That especially goes for clothes + other apparel
They all want to appear like and, in their minds, play like the archetypes in tennis, who are the top players in the world. That is why the average joe would have so much interest.